Methods and systems for adjusting an external fixation frame

ABSTRACT

A tool for implementing a correction plan in an external fixation frame having a plurality of adjustment elements or screws, for example, generally includes a driver, a motor, a controller, and a processor. The driver is adapted to engage and rotate each of the screws. The motor is coupled the driver and adapted to rotate the driver. The controller is connected to the motor and configured to control operation of the motor. The a processor adapted configured to: receive correction plan data; receive identification data including information for identifying at least one of the plurality of screws; determine movement of at least one of the plurality of the screws based on the correction plan data and the identification data; and send signals indicative of the determined movement to the controller in order to rotate at least one of the plurality of screws according to a predetermined correction plan.

BACKGROUND OF THE INVENTION

The present disclosure relates to methods, tools and systems foradjusting an external fixation frame. More particularly, the presentdisclosure relates to methods tools and system for repositioning thecomponents of an external fixation frame according to a correction plan.

The external fixation market can be divided into two major segments:acute trauma and reconstructive. The customers, products, and needs ofeach segment are distinctly different. The trauma segment is dominatedby modular fixators. These frames are characterized by limitedcomponentry and very rapid application. Consequently, they are known forbeing fairly simple products. Most of these frames are used fortemporizing fixation and quite often are only on the patient for hoursor days.

The reconstructive segment leans heavily toward ring fixation. Ringfixators, such as the well known Ilizarov frame, are very popular. Suchframes are shown in U.S. Pat. Nos. 4,365,624; 4,615,338; 4,978,348;5,702,389; and 5,971,984. Their use of a combination of pins and wiresto achieve a variety of polyaxial pin/wire attachments providesstability. They can accomplish a full six degrees of freedom and, whenapplied and managed well, can correct primary deformities while notcreating secondary deformities. Rotational deformities are the soledomain of the ring fixator. However, mastery of the techniques and theproducts themselves can be a long and daunting process that it is notattractive to many users.

It is often necessary to realign, reposition and/or securely hold twobone elements relative to one another. For example, in the practice ofmedicine, bone fragments and the like must sometimes be aligned orrealigned and repositioned to restore boney continuity and skeletalfunction. At times, this may be accomplished by sudden maneuver, usuallyfollowed by skeletal stabilization with cast, plate and screws,intramedullary devices, or external skeletal fixators.

A bone fragment can be moved, in general, from its original position asin a nonunion or malunion or from its intended position as in congenitaldeformities along six separate movements or degrees of freedom, acombination of three orthogonal translational axes (e.g., typical “X,”“Y” and “Z” axes) and three orthogonal rotational axes (e.g., rotationabout such typical “X,” “Y” and “Z” axes).

External fixation devices are attached to the boney skeleton withthreaded and/or smooth pins and/or threaded and/or smooth and/or beadedwires. Such constructs are commonly referred to as orthopaedic externalfixators or external skeletal fixators. External fixators may beutilized to treat acute fractures of the skeleton, soft tissue injuries,delayed union of the skeleton when bones are slow to heal, nonunion ofthe skeleton when bones have not healed, malunion whereby broken orfractures bones have healed in a malposition, congenital deformitieswhereby bones develop a malposition, and bone lengthening, widening, ortwisting.

A circumferential external fixator system was disclosed by G. A.Ilizarov during the early 1950s. The Ilizarov system includes at leasttwo rings or “halos” that encircle a patient's body member (e.g., apatient's leg), connecting rods extending between the two rings,transfixation pins that extend through the patient's boney structure,and connectors for connecting the transfixation pins to the rings. Useof the Ilizarov system to deal with angulation, translation and rotationis disclosed in “Basic Ilizarov Techniques,” Techniques inOrthopaedics®, Vol. 5, No. 4, December 1990, pp. 55-59.

Prior art orthopaedic external fixators differ in their ability to moveor adjust one bone fragment with respect to the other in a gradualfashion. Some allow gradual translation, others allow gradual rotationabout two axes. The Ilizarov system can provide an external fixationdevice that could provide gradual correction along and about six axes;however, such a device would require many parts and would be relativelycomplicated to build and use in a clinical situation.

Often orthopaedic external fixators such as Ilizarov fixators must berepositioned after their initial application. Such modification may benecessary to convert from one correctional axis to another or to convertfrom an initial adjustment type of fixator to a weight bearing type offixator, some of the correctional configurations not being stable enoughfor weight bearing.

A “Steward platform” is a fully parallel mechanism used in flight andautomotive simulators, robotic end-effectors, and other applicationsrequiring spatial mechanisms with high structural stiffness and includesa base platform, a top platform, and six variable limbs extendingbetween the base and top platforms. See S. V. Sreenivasan et al.,“Closed-Form Direct Displacement Analysis of a 6-6 Stewart Platform,”Mech. Mach. Theory, Vol. 29, No. 6, pp. 855-864, 1994.

Taylor et al. U.S. Pat. No. 5,702,389, which entire disclosure isincorporated by reference herein, relates to a fixator that can beadjusted incrementally in six axes by changing strut lengths only,without requiring joints to be unclamped, etc. This patent includes afirst ring member or swash plate for attachment relative to a first boneelement; a second ring member or swash plate for attachment relative toa second bone element. Six adjustable length struts having first endsmovably attached to the first member and second ends movably attached tothe second member are provided. The first ends of the first and secondstruts are joined relative to one another so that movement of the firstend of one of the first and second struts will cause a correspondingmovement of the first end of the other strut, with the first ends of thethird and fourth struts joined relative to one another so that movementof the first end of one of the third and fourth struts will cause acorresponding movement of the first end of the other strut. The thirdand fourth struts and fifth and sixth struts are similarly joined.Second ends of the first and sixth struts joined relative to one anotherso that movement of the second end of one of the first and sixth strutswill cause a corresponding movement of the second end of the otherstrut. Second ends of the second and third struts and fourth and fifthstruts are formed in a similar manner. Thus, changing the length of thestruts effects reposition of the bone segments. The mathematics of thisadjustment is set forth in the patent and may be programmed into acomputer for use with the tool of the present invention.

As discussed above, most external fixators should be adjusted over aperiod of time to reposition bone segments. The adjustment of theexternal fixation may be implemented according to a “prescription” orcorrection plan. Physicians may adjust the external fixator at precisetimes over a period of time (e.g, on a daily basis for three weeks).Patients, however, may not desire to visit the physician's office everytime an adjustment is needed. For this reason, many external fixatorscan be adjusted by the patients themselves without the assistance of aphysician. The adjustment of the external fixator should nonethelessstrictly comply with the predetermined correction plan. In someoccasions, patients may not adjust their own external fixator accordingto the correction plan for a variety of reasons. For instance, patientsmay not understand how to use the external fixator correctly. Inaddition, when the patients themselves adjust the external fixators,physicians may not even know whether patients are in fact adjusting theexternal fixators according to the correction plan. For the foregoingreasons, it is desirable to provide a tool, system and/or method forhelping a patient implement a correction plan in an external fixator.

BRIEF SUMMARY OF THE INVENTION

The present disclosure relates to methods, systems and tools foradjusting an external fixation frame according to a correction plan. Inone embodiment, a system generally includes an identification mechanism,a tool and a processor. The identification mechanism is adapted toidentify each of a plurality of adjustment elements or screws, forexample, of an external fixation system. The tool is adapted to adjustthe external fixation frame according to a predetermined correction planby rotating the plurality of screws and includes a processor. Theprocessor is configured to: receive correction plan data including thepredetermined correction plan, the predetermined correction planincluding a schedule of adjustment times and degree of rotation of eachof the plurality of screws; receive identification data from theidentification mechanism; and determine a degree of rotation of at leastone of the plurality of the screws based on the correction plan data andthe identification data.

The identification mechanism may include RFID tags attached to each ofthe plurality of screws. Each RFID tag includes identification dataidentifying each of the plurality of screws. The tool may furtherinclude an RFID reader adapted to read the identification data of theRFID tags.

The system may further include a bus device adapted to establishcommunication, whether hard wired or wireless, to allow data transferbetween the processor of the tool and an external processor. The busdevice may include an UBS device. The external processor may be coupledto a memory module adapted to store at least one of the correction plandata or the identification data. The system may also allow for datatransfer from the tool back to the external processor.

The tool of the system described above may further include a memorymodule adapted for storing at least one of the correction plan data orthe identification data. The tool may include a driver adapted to engageand rotate each of the plurality of screws and a motor connected to thedriver and adapted to rotate the driver. In addition, the tool mayinclude a controller electronically coupled to the motor and adapted tocontrol the motor based on the correction plan data and theidentification data. Moreover, the tool may include an angular positionsensor coupled to the motor and adapted to determine an angular positionof the driver. The angular position sensor may include a rotary encoder.

The tool described above may include an alarm connected to the processand adapted to be actuated at adjustment times and a clock for measuringtime and allowing the processor to actuate the alarm at the adjustmenttimes. The alarm may include a buzzer adapted to generate an audiosignal at adjustment times.

In addition, the tool may include a display unit connected to theprocessor and adapted to display correction plan data and a power supplyconnected to the processor. The power supply may include a portablebattery. The tool may further include an input device adapted to acceptinstructions from a user. The input device may include a keypad.

As discussed above, the present disclosure also relates to tools forimplementing a correction plan in an external fixation frame having aplurality of screws. In one embodiment, the tool includes a driveradapted to engage and rotate each of a plurality of screws of anexternal fixation frame; a motor coupled the driver and adapted torotate the driver; a controller connected to the motor and configured tocontrol operation of the motor; and a processor. The processor isconfigured to: receive correction plan data; receive identification dataincluding information for identifying at least one of the plurality ofscrews; determine movement of at least one of the plurality of thescrews based on the correction plan data and the identification data;and send signals indicative of the determined movement to the controllerin order to rotate at least one of the plurality of screws according toa predetermined correction plan.

The tool may further include an RFID reader adapted to receive signalscontaining identification data and originating from RFID tags attachedto each of the plurality of screws. Moreover, the tool may include a busdevice adapted to establish communication and allow data transferbetween the processor of the tool and an external processor. The busdevice may be a UBS device. In addition, the tool may include an angularposition sensor coupled to at least one of the motor or the driver. Theangular position sensor is adapted to measure an angular position of thedriver. The angular position sensor may include a rotary encoder.

The correction plan data may include adjustment times for adjusting theexternal fixation frame. The tool may include an alarm connected to theprocess and adapted to be actuated at adjustment times.

The present disclosure further relates to a computer readable mediumincluding instructions that, when executed by a processor, causes theprocessor to perform the certain steps. In one embodiment, the processoris adapted to perform the following steps: receiving correction plandata including information about a correction plan for adjusting anexternal fixation frame, the correction plan including a list ofadjustment times and positions for each of a plurality of screws of theexternal fixation frame; receiving identification data includinginformation for identifying at least one of the plurality of screws ofthe external fixation frame; and determining movement of at least one ofthe plurality of screws based on the correction plan data and theidentification data.

The present disclosure also relates to methods for implementing acorrection plan in an external fixation frame having a plurality ofscrews. In one embodiment, the methods includes the following steps:receiving correction plan data including information about a correctionplan for adjusting an external fixation frame, the correction planincluding a list of adjustment times and positions for each of aplurality of screws of the external fixation frame; receivingidentification data including information for identifying at least oneof the plurality of screws of the external fixation frame; determiningmovement of at least one of the plurality of screws based on thecorrection plan data and the identification data using a processor; andmoving at least one of the plurality of screws according to the movementdetermined by the processor.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be described withreference to the appended drawings. It is appreciated that thesedrawings depict only some embodiments of the invention and are thereforenot to be considered limiting of its scope.

FIG. 1 is a schematic diagram of a system for adjusting an externalfixation frame in accordance with an embodiment of the presentdisclosure;

FIG. 2 is an isometric view of an external fixation frame that can beused in conjunction with the system schematically depicted in FIG. 1;

FIGS. 3-4 illustrate a flowchart showing the steps executed by anadjustment application;

FIG. 5 is a flowchart illustrating a process for determining allpossible strut combinations;

FIG. 6 is a flowchart illustrating a process for determining theposition of the movable ring of the external fixation frame;

FIGS. 7 and 8 depict a flowchart illustrating a process for generating acorrection plan;

FIG. 9 is an exemplary correction plan in a table form; and

FIGS. 10-11 depict a flowchart illustrating a process for adjusting anexternal fixation frame according to a correction plan.

DETAILED DESCRIPTION

The present disclosure will now describe in detail embodiments ofmethods and systems for adjusting an external fixation frame withreference to the drawings in which like reference numerals designateidentical or substantially similar parts in each view. As used herein,“clinician” refers to a physician, surgeon, nurse or other care providerand may include support personnel.

FIG. 1 schematically depicts a tool or system 100 for adjusting anysuitable external fixation frame 10. In general, the system or tool 100includes processor 102, such as a microprocessor or central processingunit, capable of executing instructions for adjusting an externalfixation frame 10. The processor 102 may include any suitable businterface 104 for establishing communication between tool 100 and anexternal host computer 300, such as a personal computer. Suitable businterfaces 104, include, but are not limited to Universal Serial Bus(UBS), a serial port, a parallel port, IEEE 1394 interface and Ethernetbus. Regardless of its specific type, bus interface 104 allows transferof data between tool 100 and host computer 300. Host computer 300includes a processor 302 for executing instructions and a memory module304 for storing data. The bus interface 104 allows data stored on memorymodule 304 to be transferred to the tool 100. The data transfer betweentool 100 and host computer 300 may be performed directly or indirectly.For example, data may be transferred between tool 100 and host computer300 through a network, such as the Internet. The tool 100 may include amemory module 106 to store data, including data transferred from hostcomputer 300. The processor 102 can therefore retrieve and process datafrom memory module 106. If host computer 300 is connected to tool 100through bus interface 104, the processor 102 can also retrieve andprocess data stored on the memory module 304 of host computer 300.

With continued reference to FIG. 1, tool 100 may further include aninput device 108 for inputting information. Input device 108 is adaptedto accept instructions from a user and is connected to processor 102. Insome embodiments, input device 108 may include a keypad having aplurality of alphanumeric keys and/or function keys configured to beactuated by users. Users may actuate these keys by, for example,depressing and releasing the keys. Input device 108 may additionally oralternatively include any other suitable device, means or mechanisms forentering information into tool 100, such a computer mouse, touchpad,trackball, and touch screen. In one embodiment, input device 108includes a touchpad having a flat, touch sensitive screen, which tracksthe movement of a finger or stylus across it.

The tool 100 may include a display unit 110 capable of displayingimages. The display unit 110 is connected to processor 102 and mayinclude liquid crystal display (LCD) panel. As discussed in detailbelow, display unit 100 may show information pertinent to the use oftool 100.

Any suitable power supply 112 may be coupled to processor 102 forenergizing tool 100. Power supply 112 may include a DC or AC powersource and/or a battery. The battery may be rechargeable.

The tool 100 may additionally include an alarm 116 capable of generatingan audio signal or vibrations. The alarm 116 is connected to processor102. As discussed in detail below, processor 102 can executeinstructions to activate alarm 116. Alarm 116 may include a buzzer orany other device, means, or mechanism adapted for generating a sound ora vibration. As used herein, the term “sound” refers to one or moreaudio signals across the audible frequency range. Processor 102 may beconnected to a clock 118 for measuring time. Clock 118 allows theprocessor 102 to actuate the alarm 116 at specified times.

The tool 100 may further include a signal reader 120, such as aradio-frequency identification (RFID) reader, capable of reading asignal from a radio-frequency transmitter on each drive element on theframe of, as described below. This signal is indicative of theidentification of a specific screw or worm gear of the external fixationframe 10. For example, the screws may be identified by a number orletter. As discussed in detail below, each worm gear may have one ormore identification tags, such as an RFID tag, configured to send asignal to be read by the signal reader 120. The signals stemming fromthe identification contain identification data for identifying each ofthe screws of the external fixation frame 10. For example, theidentification data may be, for example, a number or letter associatedwith a specific screw.

The screws of external fixation frame 10 may be rotated by a driver 126of tool 100. Driver 126 is adapted to engage and rotate the screws ofexternal fixation frame 10. A motor 124 is connected to the driver 126.Upon activation, motor 124 can rotate driver 126. The operation andactivation of motor 124 is controlled by a motor controller 122connected to processor 102. The motor controller 122 is electronicallyconnected to an angular position sensor 125. Angular position sensor 125may include a synchro, a resolver, a rotary variable differentialtransformer (RVDT), a rotary potentiometer and/or any suitable rotaryencoder. Suitable rotary encoders for angular position sensor 125include, but are not limited to, a quadrature encoder and an absoluteencoder. The angular position sensor 125 may be disposed on the shaft ofmotor 124, on the driver 126, or on the screws. Regardless of itslocation, the angular position sensor 125 can determine the angularposition of the driver 126 and the screw attached to the driver. Duringoperation, motor controller 122 controls the operation of driver 126based on the instructions received from processor 102 and signalsreceived from angular position sensor 125. The driver 126 in turnsrotates a screw to adjust external fixation frame 10.

The tool 100 may be utilized in conjunction with any suitable externalfixation frame. In an exemplary embodiment, tool 100 is used to adjustthe external fixation frame 10 depicted in FIG. 2. In the interest ofbrevity, the present disclosure merely includes a brief description ofexternal fixation frame 10. A suitable external fixation frame isdescribed in detail in U.S. patent application Ser. No. 12/661,015 filedon Mar. 9, 2010, the entire disclosure of which is incorporated byreference herein. Another suitable external fixation frame is describedin U.S. patent application Ser. No. 12/157,612 filed Jun. 11, 2008, theentire disclosure of which is incorporated herein by reference. Themathematics of the incremental adjustments is described in theseapplications.

As seen in FIG. 2, external fixation frame 10 may be utilized with anylong bone, in particular, the tibia and the femur, and includes a firstring 14 and a second ring 16. In operation, second ring 16 remainsstationary, while ring 14 moves relative to the stationary ring 16. Insome embodiments, both rings 14, 16 are identical. Each ring 14 includesa worm gear 15 formed around its outer circumference. Two grooves 17 areformed in the upper and lower surfaces of ring 14 around itscircumference adjacent the worm gear 15. Ring 14 (or 16) may include amulti-level configuration with the upper and lower surfaces havingalternate steps including through holes 24. In certain embodiments,rings 14, 16 are connected by three variable length struts 18. The threestruts 18 have first ends 28 mounted to the first ring 14 via aconnector 25 coupled to a sliding or shuttle unit 26, which iscircumferentially moveable around ring 14. In several embodiments, thefirst ends 28 are connected to sliding or shuttle units 26 by aconnector 25 having a ball or spherical joint. As is typical, the rings14 and 16 are connected to a bone (e.g., tibia) by a plurality of bonepins or wires (not shown). In some embodiments, the pins or wires areconnected to each ring 14, 16 by connection elements, which are locatedin one or more of a multiplicity of holes 24 around the circumference ofthe first and second rings 14 and 16. Although holes 24 are shown, anystructure which locates the pins or wires with respect to thecircumference of rings 14 and 16 can be utilized. Lower ends 34 ofstruts 18 are connected to lower ring 16 by standard universal-joints35, which allow free rotation about only two axes rather than the threeaxes of the spherical joint at the first strut end 28.

Ring 14 may be coupled to a first bone element via pins or wires and,similarly, ring 16 is coupled to a second bone element by similar pinsor wires. Shuttle units 26 are slidable about ring 14 in a track and arepreferably driven by driver 126. Each shuttle unit 26 may include a wormor screw 40 configured to mesh with worm gear 15 of first ring 14. Eachscrew 40 can be driven by driver 126.

Identification tags 41, such as RFID tags, may be disposed on both sidesof each screw 40. Each identification tag 41 stores identification dataand is adapted to generate a signal indicative of the identificationdata of a particular screw 40. For instance, the identification data mayinclude a number or letter assigned to a specific screw 40. Signalreader 120 is adapted to read the signals generated from eachidentification tag 41 to identify the screw 40 associated with aparticular identification tag 41. In operation, rotation of screw 40causes shuttle unit 26 to slide about ring 14, thus changing theposition of strut 18. A second connector 29 between strut 18 and secondlower ring 16 has a standard universal joint 35, which allows the strutto rotate freely about two axes, which may be oriented perpendicular toeach other. Each universal joint 35 may include a gear portion 42 andscrew 43. Screw 43 is adapted to engage gear portion 42 and may berotated by driver 126.

Identification tags 44, such as RFID tags, may be disposed on both sidesof each screw 43. Each identification tag 44 is adapted to send a signalcontaining identification data. The identification data includesinformation distinguishing a particular screw 43 from others screws ofexternal fixation frame 10. Thus, each identification tag 44 isconfigured to generate a signal indicative of the location and identityof a particular screw 43 with respect to the entire external fixationframe 10. In addition, the signal generated by identification tag 44 maybe indicative of the side of the screw 43 where the tag is located.Signal reader 120 is adapted to read the signal generated by eachidentification tag 44 in order to identify the screw 43. Although thedrawings show screws 40 a and 43, external fixation frame mayalternatively include any drive element capable of being driven by adriver. Signal reader 120 and identification tags 41 and 44 collectivelyform an identification mechanism adapted to identify each and everyscrew 40 and 43 of external fixation frame 10. During operation,rotation of screw 43 causes gear portion 42 to pivot about a pin 1,thereby causing strut 18 to change its orientation relative to the rings14 and 16. Thus, each of the three sliding shuttle units 26 may beindependently controlled and the three connectors 29 at the second ring16 may be independently controlled so that the ring 14, and thereforethe bone element attached to ring 14, can be positioned in properalignment with ring 16 and the bone element attached to ring 16. Rings14 and 16 can be repositioned after their initial alignment as desiredby the surgeon. In addition, the movement can be programmed into aprocessor, which can automatically increment movement, for example, on adaily basis. Each strut 18 may have a variable or fixed length.

With reference to FIGS. 1 and 3, the movement of external fixation frame10 can be controlled by a computer or processor 102 of tool 100. Asdiscussed above, the processor 102 of tool 100 can communicate andinteract with host computer 300. Host computer 300 can store and executean adjustment application to execute a process 400 for controlling themovement of external fixation frame 10 over a predetermined period oftime. The memory module 304 of host computer 300 can store the dataand/or instructions necessary to run the adjustment application usingprocessor 302. The adjustment application may be a web-basedapplication.

As illustrated in FIG. 3, the adjustment application starts at block402. At block 404, adjustment application asks the clinician to inputcertain patient data. Patient data may include general information aboutthe patient to be treated, such as name, age, weight, height, or anyother information useful to identify an/or treat the patient. Theadjustment application then asks the clinician to import one or moredigital representations of the bone to be treated, at block 406. Theclinician may import a digital representation of the bone into memorymodule 304. This digital representation of the bone may be in anysuitable format. Suitable formats include, but are not limited to,Digital Imaging and Communications in Medicine (DICOM) data and digitalx-rays images.

The adjustment applicant subsequently asks the clinician to select theanatomy to be corrected. In response, the clinician may select the boneto be corrected by the external fixation frame 10, at block 408. Once ananatomy has been selected, the adjustment application prompts theclinician to input a deformity definition for the selected anatomy atblock 410. As used herein, “deformity definition” refers to theanatomical misalignment that the external fixation frame 10 willcorrect. The deformity definition (also referred as deformity data) mayinclude information about the rotation, translation, angulation, lengthand vertical translation of the selected bone or anatomy.

The adjustment application then asks the clinician to input anatomicallimiting factors (ALF) coordinates at block 412. ALF refers to factorsthat may limit the movement of the external fixation frame 10. Forexample, the correction of the selected bone should be conducted atgradual rate of bone distraction. A rapid rate of distraction may resultin a fibrous union in which the bone pieces are joined by fibrous,rather than osseous tissue. Conversely, an atypically slow distractionrate may result in early bone consolidation. It is therefore desirableto control the rate of bone distraction by inputting specificcoordinates for the movement of external fixation frame 10. The rate ofbone distraction may be, for example, set at 1 millimeter per day.Another ALF may be the position of the patient's nerves. Duringcorrection of the injured or misaligned bone, stretching of the nervesmay occur. Stretching of the nerves must not be too rapid to avoid nerveinjury. Another ALF can be the patient's skin. If the skin has beencompromised, for example in case of an open fracture that part of theskin should not be stretch too rapidly to allow the skin to heal.

At block 414, the adjustment application allows the clinician to selectthe appropriate ring size in accordance with the patient's anatomy.After selecting the ring size, the adjustment application asks theclinician whether the application should be executed in pre-operation(Pre-Op) or post-operation (Post-Op) mode, at block 416. The Pre-Op modeis an optional planning tool designed to virtually test the movement ofthe external fixation frame 10 without attaching the external fixationframe to a bone. In the Post-Op mode, the adjustment application runswhile the external fixation frame 10 is attached to a bone to correctthat bone.

If the clinician selects the Pre-Op mode of the adjustment application,the application determines all possible strut combinations based on,among other things, the positions of the rings 14 and 16, at block 418,as discussed in detail below. The adjustment application then allows theclinician to select a strut combination at block 420 out of all thepossible strut combinations. Once the clinician has selected a strutcombination, the adjustment application generates a correction plan atblock 422, as discussed in detail below. The host computer 300 thendisplays the correction plan and a simulation thereof via any suitableoutput device, such as a monitor or screen, at block 424. The hostcomputer 300 also displays a report for the specific patient at block426. The report may include, but is not limited to, patient data,selected anatomy, correction plan data, inputted deformity definition,inputted ALF coordinates, etc. The report may be displayed through anoutput device, such as a monitor, which is connected to host computer300. After running the adjustment application in the optional Pre-Optmode, the clinician may run the adjustment application in the Post-Optmode to correct the patient's bone. Accordingly, the adjustmentapplication allows the clinician to select again the mode of applicationat block 416.

If the clinician selects the Post-Op mode at block 416, the adjustmentapplication determines the position of the movable ring 14 at block 428.As discussed above, rings 14 is adapted to move during operation, whilering 16 remains stationary. The adjustment application may determine theposition of the movable ring based on, among other things, the inputteddigital representations of the bone, anatomy, deformity definition, ALFcoordinates and the strut lengths. Subsequently, the adjustmentapplication generates a correction plan at block 430, as discussed indetail below.

After generating the correction plan, the host computer 300 displays thecorrection plan and a simulation thereof, at block 432, via an outputdevice, such as a monitor or screen. In addition, the host computer 300displays a report for the specific patient at block 434. The report mayinclude, but is not limited to, patient data, selected anatomy,correction plan data, inputted deformity definition, inputted ALFcoordinates, etc. The report may be displayed through an output device,such as a monitor, which is connected to host computer 300. Thecorrection plan as well as all the necessary data is uploaded into tool100 at block 436. The host computer 300 can be connected directly totool 100 via bus interface 104. For example, a UBS cable mayinterconnect bus interface 104 and host computer 300. Alternatively,communication between host computer 300 and tool 100 may be establishedthrough a closed network or an open network, such and the Internet. Ifcommunication is established through a network, the tool 100 may beconnected to the network through another computer. In such case, thetool 100 is connected to that computer via bus interface 104. Thatcomputer is in turn connected to the network and interacts andcommunicates with host computer 300. The adjustment applicationterminates, at block 438, after the correction plans is uploaded to tool100.

FIG. 5 illustrates a process 500 for determining all possible strutcombinations in the Pre-Op mode of the adjustment application, asdiscussed above with respect to block 418 of FIG. 4. This process beginsat block 502 of FIG. 5. To determine the possible strut combinations,the adjustment application allows the clinician to input ring data atblock 504. Ring data may include, but is not limited to, sizes of bothrings 14 and 16, three-dimensional position (i.e., X,Y,Z coordinates) ofthe ring 16 with respect to reference coordinates (i.e., origin) and thethree-dimensional position (i.e., X,Y,Z coordinates) of ring 14 withrespect to reference coordinates (i.e., origin). After inputting thering data, the adjustment application updates a preloaded digitalrepresentation of external fixation frame 10 with the inputted ring dataat block 504. The digital representation of external fixation frame 10may be updated with the new dimensions, positions, offsets and angles ofthe rings 14 and 16. In one exemplary method, the digital representationof external fixation frame 10 (e.g., 3D digital model) may be createdwith any suitable 3D modeling or computer aided design (CAD) software,such as the Pro/E® or Creo Elements/Pro™ sold by Parametric TechnologyCorporation. The digital representation of external fixation frame 10may be updated using any programming interface to the 3D modeling or CADsoftware. For instance, the digital representation of external fixationframe 10 may be updated with an application programming interface (API),such as the Java-based API J/Link™ sold by Parametric TechnologyCorporation. J/Linkυ, for example, integrates Pro/E® and Java, allowingthe Pro/E® model to be modified with a Java program.

After the digital representation of data has been updated with theinputted ring data, the 3D modeling or CAD software regenerates the 3Dmodel of the external fixation frame 10 and the patient's anatomy, atblock 508, based on the initial strut combination. As used herein, a“strut combination” refers the struts 18 connected rings 14 and 16,which may have different sizes and/or length. For example, one strutcombination may include struts 18 having the same lengths. Another strutcombination may entail two struts 18 having the same lengths and a thirdstrut having a different length. Yet another strut combination mayinclude three struts 18 all having different lengths. Since externalfixation frame 10 has a plurality of struts 18, it can have multiplestrut combinations. At block 508, the CAD software regenerates a 3Dmodel of external fixation frame 10 and the patient's anatomy with aninitial strut combination.

At block 510, the 3D model is regenerated for a different strutcombination. As discussed above, the 3D model may be regenerated usingany suitable 3D modeling or CAD software. Once the 3D model of externalfixation frame 10 and the patient's anatomy has been regenerated for thespecific strut combination, the adjustment application determines, atdecision block 512, whether the fail distance for any of the struts 18is zero. Fail distance may be defined as a position of a strut outsideof its possible position or angle with respect to a ring of fixationframe 10. If the fail distance for any of the struts 18 is not zero forthe specific strut combination, then the adjustment application discardsthat strut combination and regenerates a 3D model for another strutcombination at block 510. Conversely, if the fail distance for all thestruts 18 is zero for the specific strut combination, then theadjustment application determines whether the angles between shuttleunits 26 are each greater than or equal to 45° at decision block 514. Ifeach of these angles is not greater than or equal to 45°, the adjustmentapplication discards that strut combination and regenerates a 3D modelfor another strut combination at block 512. On the other hand, if eachof these angles is greater than or equal to 45°, the adjustmentapplication then determines whether each of the angles defined betweeneach gear portions 42 and stationary ring 16, for that specific strutcombination, is within a specified range, preferably between 0° and 120°at decision block 516. If any of these angles is not between 0° and120°, the adjustment application then discards that specific strutcombination and regenerates the 3D model for another strut combination.If each of these angles is between 0° and 120°, the adjustmentapplication then adds the strut combination to a list of all possiblecombinations.

Once the specific strut combination has been added to the list ofpossible strut, the adjustment application determines whether allconceivable strut combinations have been analyzed by process 500 atdecision block 520. If all conceivable strut combinations have beenanalyzed, the adjustment application terminates at block 522. On theother hand, if not all conceivable strut combinations have beenanalyzed, then the adjustment application regenerates a 3D model ofexternal fixation frame 10 with a different strut combination at block510 and analyzes such strut combination as described above.

As discussed above with regard to FIGS. 3 and 4, the adjustmentapplication executes a process 400, which includes determining theposition of a movable ring 14, at block 428, in the Post-Op mode. Todetermine the position of the movable ring 14, the adjustmentapplication may execute the process 600 illustrated in FIG. 5.

FIG. 6 illustrates the process 600 for determining the position ofmovable ring 14, which starts at block 602. The adjustment applicationallows the clinician to input frame data at block 604. Frame data mayinclude, but is not limited to, sizes of both rings 14 and 16, thelengths of struts 18, orientation of shuttle units 26 and gear portions42. The inputted information about the orientation of the shuttle units26 and gear portions 42 may include the angles that each of the shuttleunits 26 and gear portions 42 are with respect to the struts 18. Afterinputting the frame data, the adjustment application updates a preloadeddigital representation of external fixation frame 10 (i.e., digitalmodel) with the inputted frame data at block 606. The digitalrepresentation of external fixation frame 10 may be updated with the newdimensions, positions, offsets and angles of the rings 14 and 16. In oneexemplary method, the digital representation of external fixation frame10 (e.g., 3D model) may be created with any suitable 3D modeling orcomputer aided design (CAD) software, such as the Pro/E® or CreoElements/Pro™ sold by Parametric Technology Corporation. The digitalrepresentation of external fixation frame 10 may be updated using anyprogramming interface to the 3D modeling or CAD software. For instance,the digital representation of external fixation frame 10 may be updatedwith an application programming interface (API), such as the Java-basedAPI J/Link™ sold by Parametric Technology Corporation. J/Link™, forexample, integrates Pro/E® and Java, allowing the Pro/E® model to bemodified with a Java program. After the digital representation of datahas been updated with the inputted ring data, the 3D modeling or CADsoftware regenerates the 3D model of the external fixation frame 10 andthe patient's anatomy, at block 608, based on the inputted frame data.

At block 610, the adjustment application determines distances betweeneach of connectors 25 and the struts 14. At decision block 612, theadjustment application subsequently determines if all of the distancesdetermined at block 610 are zero. If any of the determined distances isnot zero, an error notification is displayed on any suitable outputdevice, such as a monitor or screen, at block 614. The errornotification may include the following message: “Invalid InputParameters.” After displaying the error notification, the adjustmentapplication allows the clinician to new input frame data at block 604.If all the distances determined at block 610 are zero, the adjustmentapplication runs the transformations on the digital model of externalfixation frame 10, at block 616. As discussed above, the digital modelmay be created with any suitable 3D modeling or CAD software, such asthe Pro/E® or Creo Elements/Pro™ sold by Parametric TechnologyCorporation. Then, the adjustment application determines valuesconcerning the position of movable ring 14. These values may include theoffset and orientation of the center of movable ring 14 in the coronal,sagital and axial planes. After determining these values, the process600 ends at block 620.

As discussed above, the adjustment application can generate a correctionplan either in the Pre-Op mode or Post-Op mode. To generate thecorrection plan, the adjustment application executes the process 700depicted in FIG. 7. The process 700 begins at block 702 and then allowsa clinician to input frame data at block 704. The frame data mayinclude, but is not limited to the sizes of the rings 14 and 16, theosteotomy position, the three dimensional position and orientation ofring 14 with respect to an origin, deformity definitions in the coronal,sagital and axial planes, angles of the shuttle units 26 and gearportions 42 with respect the struts 18, and correction time. Thecorrection time may be expressed in days.

With continued reference to FIG. 7, after inputting the frame data, theadjustment application updates a preloaded digital representation ofexternal fixation frame 10 (i.e., digital model) with the inputted framedata at block 704. The digital representation of external fixation frame10 may be updated with the new dimensions, positions, offsets and anglesof the rings 14 and 16. In one exemplary method, the digitalrepresentation of external fixation frame 10 (e.g., 3D digital model)may be created with any suitable 3D modeling or computer aided design(CAD) software, such as the Pro/E® or Creo Elements/Pro™ sold byParametric Technology Corporation. The digital representation ofexternal fixation frame 10 may be updated using any programminginterface to the 3D modeling or CAD software. For instance, the digitalrepresentation of external fixation frame 10 may be updated with anapplication programming interface (API), such as the Java-based APIJ/Link™ sold by Parametric Technology Corporation. J/Link™, for example,integrates Pro/E® and Java, allowing the Pro/E® model to be modifiedwith a Java program. After the digital representation of data has beenupdated with the inputted frame data, the 3D modeling or CAD softwareregenerates the digital model of the external fixation frame 10 and thepatient's anatomy, at block 708, based on the inputted frame data.

Once the digital model has been regenerated in the 3D modeling or CADsoftware, the adjustment application calculates the distance (d) betweenthe initial bone deformity position and the final bone deformityposition (i.e., reference point.) The adjustment application thencalculates the correction steps. In one exemplary method, the correctiontime may be determined by dividing the distance (d) between the initialand final bone deformity positions by the inputted correction time. Asdiscussed above, the correction time may be expressed in days.

The adjustment application subsequently calculates the initial targetposition of movable ring 14, at block 714, based on the initial positionof movable ring 14 and the inputted deformity definitions. Then, theadjustment application calculates the daily target positions of movablering 14, at block 716, based on the initial and final target positionsof the movable ring 14 and the number of correction steps. At block 718,the adjustment application then regenerates the digital model ofexternal fixation frame 10 for every daily target position using themovable ring position, the reference ring position, and the strutslengths. The digital model of external fixation frame 10 may beregenerated with any 3D modeling or CAD software, as described above.

After regenerating the digital model of external fixation frame 10, theadjustment application determines whether virtual model of the externalfixation frame 10 is located outside of its workspace at any of thedaily target positions at decision block 720. The external fixationframe cannot move outside of its workspace. Accordingly, the correctionplan should include daily target positions compatible with the workspaceof the external fixation frame 10. If the digital model of externalfixation frame 10 is outside the allowed workspace for any daily targetposition, the adjustment application employs the next available strutcombination from the list of all possible strut combinations determinedby the process 500 at block 722 and, subsequently, regenerates thedigital model again for every daily target position at block 718. If thedigital model of external fixation frame 10 is within its allowedworkspace for every daily target position, the adjustment applicationthen determines the angles of the shuttle unit 26 and gear portions 42relative to the struts 18 at block 724. After determining these angles,the adjustment application updates the correction plan at block 726 withthe angles determined at block 724. The updated correction plan mayreflect changes in the strut combination. The updated correction plan or“prescription” may be in the form of a table, as shown in FIG. 9 and mayinclude screw identification data (e.g., screw number or letter), amountof rotation (e.g., degrees or radians), direction of rotation (e.g.,clockwise or counterclockwise), and frequency of rotation (e.g., inhours and minutes.) The process 700 ends after the adjustmentapplication has updated the correction plan at block 728.

With reference to FIG. 1, tool 100 includes a processor 102 adapted toexecute a correction application stored on memory module 106. Memorymodule 106 may store a correction plan data used by the correctionapplication. The correction application may be used in conjunction withtool 100 to implement a correction plan algorithm or process.

FIGS. 10 and 11 illustrate a flowchart of the correction algorithm orprocess 800, which starts at block 802. At block 804, correction plandata generated by adjustment application, as described above, isdownloaded to tool 100. The correction plan data is stored on memorymodule 106 and may include, but is not limited to, screw identificationinformation (e.g., screw number or letter), amount of rotation (e.g.,degrees or radians), direction of rotation (e.g., clockwise orcounterclockwise), and frequency of rotation (e.g., in hours andminutes.) The correction application then validates the correction plandata by, for example, verifying that the data is not corrupted. Theclinician is also given the opportunity to validate the correction planat decision block 808. Accordingly, the correction plan allows theclinician to input whether the correction plan is valid via input device108 of tool 100. If the correction application or the cliniciandetermines that the correction plan is not valid, the correctionapplication displays an error notification or message, such as“Correction Plan Invalid,” at block 810, and then allows the clinicianor the patient to input a valid correction plan at block 804. The errornotification may be displayed via display unit 110 of tool 100. If thecorrection plan is valid, the application plan reads the correction plandata stored on memory module 106 to retrieve the start date of thecorrection plan at block 812.

Based on the retrieved start date, the correction application determinesor calculates the precise time (i.e., adjustment time) of the firstcorrection, at block 814. The correction application then actuates alarm116 to alert the patient that is time to execute a scheduled correctionat block 816. Specifically, processor 102 receives a signal from clock118 at the adjustment time. In response to this signal, the processor102 sends a signal to alarm 115 to actuate it. At block 818, the patientor clinician may then activate the signal reader 120 of tool 100 toidentify the screw to be rotated according to the downloaded correctionplan. As discussed above, the signal reader 120 may be an RFID reader.The signal reader 120 is then moved close to a screw 40 or 43 to readsignal generated by the identification tags 41 or 44 in each screw 40 or43. Once the signal reader 120 reads the signal from the identificationtags 41 or 44, the processor 102 of tool 100 identifies the screw. Thecorrection application then determines whether the identified screwcorresponds to the screw that needs to be rotated according to thedownloaded correction plan at decision block 820. If the identifiedscrew does not need to be rotated at that precise moment (i.e.,scheduled adjustment time), an error notification is displayed viadisplay unit 110, at block 822, and the alarm 116 is actuated at block824 to indicate the user that the identified screw does not need to berotated at the moment. The error notification may include an errormessage, such as “Invalid Screw.” The error message may be displayed atthe same time as the alarm is actuated. In response to the errornotification, the user may use signal reader 120 to identify theappropriate screw 40 or 43.

If the signal reader 120 identifies the screw 40 that should be rotatedaccording to the correction plan, the user may then securely engagedriver 126 to the identified screw 40 or 43. Subsequently, the useractivates the motor 124 to rotate the identified screw 40 or 43 at block826. While the identified screw 40 or 43 rotates, the angular positionsensor 125 measures the angular position of the rotating screw at block828. The angular position sensor 125 sends 125 a signal indicative ofthe angular position of the identified screw 40 or 43 to the motorcontroller 122. Based on this signal, the motor controller 122determines whether the identified screw 40 or 43 has been rotatedaccording to the correction plan at block 830. If the screw has not beencompletely rotated in accordance with the correction plan, then themotor controller 124 instructs the motor 124 to continue rotating thedriver 126 until the identified screw 40 or 43 has been rotated inaccordance with the correction plan. Conversely, if the identified screwhas been completely rotated according to the correction plan, the motorcontroller 122 instructs the motor 126 to stop rotating driver 126. Thecorrection application then records when the identified screw wasrotated (i.e., execution time) and the status of the rotated screw(e.g., angular position of rotated screw). This information may bestored on memory module 106.

The system preferably includes a safety feature to ensure that theadjustment elements are rotated the correct amount when being adjustedby the tool. In rare circumstances, the driver may disengage from thescrew head during rotation. In such a case, the system would receive asignal response alerting it that the driver has disengaged from thescrew head, allowing the tool to re-engage the adjustment element and toadjust the element the amount it would have been adjusted but for theprevious disengagement.

At block 834, the correction application determines whether any otherscrew needs to be rotated immediately in accordance with the correctionplan. If more screws need to be rotated, the processor 102 retrieves andreads the adjustment data for the next screw at block 836. Then, theuser may identify the correct screw, at block 818, and rotate said screwas described above. On the other hand, if the correction plan does notprovide for immediate rotation of other screws, the correctionapplication determines whether any other corrections are necessary inthe future, at decision block 838. If more corrections are necessary,the processor 102 determines or calculates the time for the nextcorrection at block 840. At block 842, the correction time may bedisplayed through display unit 110. The clock 118 measures time andsends a signal to processor 102 at the next correction time. In responseto this signal, the processor 102 actuates alarm 116 at block 816. Thecorrection plan then executes the necessary steps to rotate theappropriate screws in accordance with the correction plan, as discussedin detail above. If no more corrections are necessary, the display unit110 displays a message or notification indicating that the correction ofbone has finished. The message may be, for example, “CorrectionFinished.” The correction application then terminates process 800 atblock 846.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

1. A system for implementing a correction plan in an external fixationframe having a plurality of adjustment elements, comprising: anidentification mechanism adapted to identify each of a plurality ofadjustment elements of an external fixation system; and a tool adaptedto adjust the external fixation frame according to a predeterminedcorrection plan by rotating the plurality of adjustment elements, thetool comprising: a processor configured to: receive correction plan dataincluding the predetermined correction plan, the predeterminedcorrection plan including a schedule of adjustment times and degree ofrotation of each of the plurality of adjustment elements; receiveidentification data from the identification mechanism; and determine adegree of rotation of at least one of the plurality of the adjustmentelements based on the correction plan data and the identification data.2. The system according to claim 1, wherein the identification mechanismincludes RFID tags attached to each of the plurality of adjustmentelements, each RFID tag including identification data identifying eachof the plurality of adjustment elements.
 3. The system according toclaim 2, wherein the tool further comprise an RFID reader adapted toread the identification data of the RFID tags.
 4. The system accordingto claim 1, further comprising a bus device adapted to establishcommunication and allow data transfer between the processor of the tooland an external processor.
 5. The system according to claim 4, whereinthe bus device includes an UBS device.
 6. The system according to claim4, wherein the external processor is coupled to a memory module adaptedto store at least one of the correction plan data or the identificationdata.
 7. The system according to claim 1, wherein the tool includes amemory module adapted for storing at least one of the correction plandata or the identification data.
 8. The system according to claim 1,wherein the tool includes a driver adapted to engage and rotate each ofthe plurality of adjustment elements.
 9. The system according to claim8, wherein the tool includes a motor connected to the driver and adaptedto rotate the driver.
 10. The system according to claim 9, wherein thetool includes a controller electronically coupled to the motor andadapted to control the motor based on the correction plan data and theidentification data.
 11. The system according to claim 9, wherein thetool includes an angular position sensor coupled to the motor andadapted to determine an angular position of the driver.
 12. The systemaccording to claim 11, wherein the angular position sensor includes arotary encoder.
 13. The system according to claim 1, wherein the toolincludes an alarm connected to the process and adapted to be actuated atadjustment times.
 14. The system according to claim 13, wherein the toolincludes a clock for measuring time and allowing the processor toactuate the alarm at the adjustment times.
 15. The system according toclaim 13, wherein the alarm includes a buzzer adapted to generate anaudio signal at adjustment times.
 16. The system according to claim 1,wherein the tool includes a display unit connected to the processor andadapted to display correction plan data.
 17. The system according toclaim 1, wherein the tool includes a power supply connected to theprocessor.
 18. The system according to claim 17, wherein the powersupply includes a portable battery.
 19. The system according to claim 1,wherein the tool includes an input device adapted to accept instructionsfrom a user.
 20. The system according to claim 19, wherein the inputdevice includes a keypad.
 21. A tool for implementing a correction planin an external fixation frame having a plurality of adjustment elements,comprising: a driver adapted to engage and rotate each of a plurality ofadjustment elements of an external fixation frame; a motor coupled thedriver and adapted to rotate the driver; a controller connected to themotor and configured to control operation of the motor; a processoradapted configured to: receive correction plan data; receiveidentification data including information for identifying at least oneof the plurality of adjustment elements; determine movement of at leastone of the plurality of the adjustment elements based on the correctionplan data and the identification data; and send signals indicative ofthe determined movement to the controller in order to rotate at leastone of the plurality of adjustment elements according to a predeterminedcorrection plan.
 22. The tool according to claim 21, further comprisingan RFID reader is adapted to receive signals containing identificationdata and originating from RFID tags attached to each of the plurality ofadjustment elements.
 23. The tool according to claim 21, furthercomprising a bus device adapted to establish communication and allowdata transfer between the processor of the tool and an externalprocessor.
 24. The tool according to claim 23, wherein the bus device isa UBS device.
 25. The tool according to claim 23, further comprising anangular position sensor coupled to at least one of the motor or thedriver, the angular position sensor being adapted to measure an angularposition of the driver.
 26. The tool according to claim 25, wherein theangular position sensor includes a rotary encoder.
 27. The toolaccording to claim 21, wherein the correction plan data includesadjustment times for adjusting the external fixation frame.
 28. The toolaccording to claim 27, further comprising an alarm connected to theprocess and adapted to be actuated at adjustment times.
 29. A computerreadable medium including instructions that, when executed by aprocessor, causes the processor to perform the following steps:receiving correction plan data including information about a correctionplan for adjusting an external fixation frame, the correction planincluding a list of adjustment times and positions for each of aplurality of adjustment elements of the external fixation frame;receiving identification data including information for identifying atleast one of the plurality of adjustment elements of the externalfixation frame; and determining movement of at least one of theplurality of adjustment elements based on the correction plan data andthe identification data.
 30. A method for implementing a correction planin an external fixation frame having a plurality of adjustment elements,comprising: receiving correction plan data including information about acorrection plan for adjusting an external fixation frame, the correctionplan including a list of adjustment times and positions for each of aplurality of adjustment elements of the external fixation frame;receiving identification data including information for identifying atleast one of the plurality of adjustment elements of the externalfixation frame; determining movement of at least one of the plurality ofadjustment elements based on the correction plan data and theidentification data using a processor; and moving at least one of theplurality of adjustment elements according to the movement determined bythe processor.